fix(build): pin turbopack.root, update comment for middleware to proxy rename (#897)

Pins turbopack.root to the project directory so a parent-directory lockfile cannot make Turbopack misdetect the workspace root, and updates a stale comment reference (middleware.ts is now proxy.ts). The rename itself already landed on main.

app/(auth)/auth/callback/route.ts

@@ -26,7 +26,7 @@ export async function GET(request: NextRequest) {
           cookiesToSet.forEach((cookie) => {
             // Mirror the cookie into request.cookies so subsequent getAll()
             // calls within this request lifecycle return the updated values
-            // (matches the pattern used in middleware.ts).
+            // (matches the pattern used in proxy.ts).
             request.cookies.set(cookie.name, cookie.value)
             pendingCookies.push(cookie)
           })

next.config.ts

@@ -1,8 +1,12 @@
+import path from "node:path";
+import { fileURLToPath } from "node:url";
 import type { NextConfig } from "next";
 import createNextIntlPlugin from "next-intl/plugin";
 
 const withNextIntl = createNextIntlPlugin("./i18n/request.ts");
 
+const projectRoot = path.dirname(fileURLToPath(import.meta.url));
+
 const isDev = process.env.NODE_ENV === "development";
 
 const supabaseUrl = process.env.NEXT_PUBLIC_SUPABASE_URL ?? "";
@@ -33,6 +37,11 @@ const cspDirectives = [
 
 const nextConfig: NextConfig = {
   output: 'standalone',
+  // Multiple lockfiles exist above this project (e.g. a parent yarn.lock),
+  // which makes Turbopack infer the wrong workspace root. Pin it explicitly.
+  turbopack: {
+    root: projectRoot,
+  },
   async redirects() {
     return [
       {